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From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Jason Gunthorpe <jgg@mellanox.com>,
	Hector Marco-Gisbert <hecmargi@upv.es>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Russell King <linux@armlinux.org.uk>,
	Will Deacon <will@kernel.org>, Jann Horn <jannh@google.com>,
	x86@kernel.org, linux-arm-kernel@lists.infradead.org,
	kernel-hardening@lists.openwall.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/6] x86/elf: Add table to document READ_IMPLIES_EXEC
Date: Thu, 12 Mar 2020 17:06:01 -0700
Message-ID: <202003121705.6ABA79D8F0@keescook> (raw)
In-Reply-To: <20200311194446.GL3470@zn.tnic>

On Wed, Mar 11, 2020 at 08:44:46PM +0100, Borislav Petkov wrote:
> Ozenn Mon, Feb 24, 2020 at 09:13:02PM -0800, Kees Cook wrote:
> > Add a table to document the current behavior of READ_IMPLIES_EXEC in
> > preparation for changing the behavior.
> > 
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
> > ---
> >  arch/x86/include/asm/elf.h | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> > 
> > diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> > index 69c0f892e310..733f69c2b053 100644
> > --- a/arch/x86/include/asm/elf.h
> > +++ b/arch/x86/include/asm/elf.h
> > @@ -281,6 +281,25 @@ extern u32 elf_hwcap2;
> >  /*
> >   * An executable for which elf_read_implies_exec() returns TRUE will
> >   * have the READ_IMPLIES_EXEC personality flag set automatically.
> > + *
> > + * The decision process for determining the results are:
> > + *
> > + *              CPU: | lacks NX*  | has NX, ia32     | has NX, x86_64 |
> > + * ELF:              |            |                  |                |
> > + * -------------------------------|------------------|----------------|
> > + * missing GNU_STACK | exec-all   | exec-all         | exec-all       |
> > + * GNU_STACK == RWX  | exec-all   | exec-all         | exec-all       |
> > + * GNU_STACK == RW   | exec-none  | exec-none        | exec-none      |
> 
> In all those tables, you wanna do:
> 
> s/GNU_STACK/PT_GNU_STACK/g
> 
> so that it is clear what this define is.

Fair enough. :) I think I was trying to save 3 characters from earlier
tables that were wider. I'll send a v5.

Thanks!

-Kees

-- 
Kees Cook

  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-25  5:13 [PATCH v4 0/6] binfmt_elf: Update READ_IMPLIES_EXEC logic for modern CPUs Kees Cook
2020-02-25  5:13 ` [PATCH v4 1/6] x86/elf: Add table to document READ_IMPLIES_EXEC Kees Cook
2020-03-11 19:44   ` Borislav Petkov
2020-03-13  0:06     ` Kees Cook [this message]
2020-02-25  5:13 ` [PATCH v4 2/6] x86/elf: Split READ_IMPLIES_EXEC from executable GNU_STACK Kees Cook
2020-02-25  5:13 ` [PATCH v4 3/6] x86/elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces Kees Cook
2020-02-25  5:13 ` [PATCH v4 4/6] arm32/64, elf: Add tables to document READ_IMPLIES_EXEC Kees Cook
2020-02-25  5:13 ` [PATCH v4 5/6] arm32/64, elf: Split READ_IMPLIES_EXEC from executable GNU_STACK Kees Cook
2020-02-25  5:13 ` [PATCH v4 6/6] arm64, elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces Kees Cook

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